37* 



PLANT RESPONSE 



more active upper, to the less active lower end, or downwards. 

 The record will be seen to verify this anticipation in every 

 particular (fig. 161). Cold water was applied below — repre- 

 sented by x in the record — which before application was 

 horizontal. After this we observe^ a movement of water 

 upwards, at a rate of four cubic mm. per minute. The upward 

 flow continues for about seven minutes, by which time the 



Fig. 161. Record obtained by Method of Hydrostatic Balance of 

 Successive Applications of Cold and Warm Water 



After obtaining static balance, with horizontal record not shown in the 

 figure, cold water was applied below at moment x . The transitory 

 excitation thus occasioned causes movement of water upwards, followed 

 by depression and reversal of flow downwards. Warm water next 

 applied at f causes second reversal and flow of water upwards. 



activity of the lower end of the specimen has become so 

 depressed as to cause reversal of the flow, which is now from 

 above downwards at an average rate of about six cubic mm. 

 per minute. This record was taken continuously for some 

 time, when hot water was quickly substituted for cold, in the 

 plant-vessel. A cross marks this point in the record. 



(b) Action of warm water. — The result was not only that 



